#include <bits/stdc++.h>
#include <chrono>
using namespace std;
#define reps(i,s,n) for(int i = s; i < n; i++)
#define rep(i,n) reps(i,0,n)
#define Rreps(i,n,e) for(int i = n - 1; i >= e; --i)
#define Rrep(i,n) Rreps(i,n,0)
#define ALL(a) a.begin(), a.end()
#define fi first
#define se second
typedef long long ll;
typedef vector<ll> vec;
typedef vector<vec> mat;

ll N,M,H,W,Q,K,A,B;
string S;
typedef pair<ll, ll> P;
const ll INF = (1LL<<58);

int main() {
    cin>>N>>M;
    map<ll, vec> cb;
    rep(i,M){
        ll b, c;
        cin>>b>>c;
        cb[c].push_back(b);
    }
    ll ans = N * (N + 1) / 2;
    unordered_map<int, bool> used;
    for(auto ite = cb.rbegin(); ite != cb.rend(); ++ite){
        ll parent = ite->fi;
        queue<ll> que;
        for(ll to : ite->se) {
            if(!used[to] && parent > to){
                used[to] = true;
                que.push(to);
            }
        }
        while(!que.empty()){
            ll now = que.front(); que.pop();
            ans += parent - now;
            for(ll to : cb[now]){
                if(!used[to] && parent > to){
                    used[to] = true;
                    que.push(to);
                }
            }
        }
    }
    cout<<ans<<endl;
}